Open source proof-of-work projects
Every project in the registry tagged proof-of-work, ranked by real GitHub adoption.
Privacy-first CAPTCHA alternative with proof-of-work
Next-Gen CAPTCHA and Spam Protection, GDPR compliant
Privacy-first proof-of-work CAPTCHA without user friction
GDPR-compliant bot protection without user friction
Invisible bot protection that respects user privacy
Related tags
Frequently asked questions
How many open source proof-of-work projects are there?
This registry tracks 5 projects tagged proof-of-work, with 13,273 GitHub stars between them. The most-adopted is Cap at 7,798 stars.
Are these proof-of-work projects free to use?
Yes — 3 of the 5 carry an explicit open-source licence across 3 distinct licences, so there is no licence fee. Where a project also sells a hosted or enterprise version, the self-hosted path remains free.
Which proof-of-work project should I choose?
The list above is ranked by GitHub stars, but stars measure attention rather than fit. Check three things on each card: the licence (permissive versus copyleft), the language it is written in, and the last-push date — a high-star project that has not been pushed in a year is a liability.
Are these proof-of-work projects still maintained?
4 of the 5 were pushed in the last 90 days, and every card shows its exact last-push date so you can see the rest. Sort your shortlist by that date before committing to a migration.